Flame-retardant cross-linked EPDM rubber

ABSTRACT

In an example, a process includes polymerizing a mixture that includes an ethylene monomer, a propylene monomer, and a diene monomer to form an ethylene-propylene-diene (EPDM) terpolymer using ring-opening metathesis polymerization (ROMP). The process further includes chemically reacting the EPDM terpolymer with a norbornene-based phosphinate cross-linking material to form a flame-retardant, cross-linked EPDM rubber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/867,404, filed Sep. 28, 2015, currently granted as U.S. Pat. No.9,879,121. The aforementioned related patent application is hereinincorporated by reference in its entirety.

I. FIELD OF THE DISCLOSURE

The present disclosure relates generally to flame-retardant,cross-linked ethylene-propylene-diene (EPDM) rubber.

II. BACKGROUND

Some high performance computing systems have migrated to water coolingsolutions in order to more effectively remove heat. In some case, awater cooling system design may utilize flexible tubing in order toallow for incorporation of a large number of connections to coldplates/heat sinks. As cooling designs evolve to bring cooling insidenodes, reliability becomes a more important design consideration inorder to reduce risk of catastrophic failure of electrical components.

III. SUMMARY OF THE DISCLOSURE

According to an embodiment, a process includes polymerizing a mixturethat includes an ethylene monomer, a propylene monomer, and a dienemonomer to form an ethylene-propylene-diene (EPDM) terpolymer usingring-opening metathesis polymerization (ROMP). The process furtherincludes chemically reacting the EPDM terpolymer with a norbornene-basedphosphinate cross-linking material to form a flame-retardant,cross-linked EPDM rubber.

According to another embodiment, a process includes polymerizing amixture that includes a chlorinated ethylene monomer, a propylenemonomer, and a diene monomer to form a chlorinated EPDM terpolymer usingROMP. The process also includes chemically reacting a norbornene-basedalcohol and a phosphinate material to form a norbornene-basedphosphinate cross-linking material. The process further includeschemically reacting the chlorinated EPDM terpolymer with thenorbornene-based phosphinate cross-linking material to form aflame-retardant, cross-linked chlorinated EPDM rubber.

According to another embodiment, an article of manufacture is disclosedthat includes a flame-retardant, cross-linked EPDM rubber that iscross-linked using a norbornene-based phosphinate cross-linkingmaterial.

An advantage of the present disclosure is the ability to incorporateflame retardancy characteristics to an EPDM rubber by directly attachinga flame retardant agent (e.g., phosphorus) to an EPDM terpolymer via anorbornene-based phosphinate cross-linking agent using ROMP. In somecases, a chlorinated ethylene monomer may be used to form a chlorinatedEPDM terpolymer. Incorporating a halogen, such as chlorine, directlyinto an EPDM polymer chain may also provide flame retardancy benefits.

Features and other benefits that characterize embodiments are set forthin the claims annexed hereto and forming a further part hereof. However,for a better understanding of the embodiments, and of the advantages andobjectives attained through their use, reference should be made to theDrawings and to the accompanying descriptive matter.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chemical reaction diagram showing the preparation of aflame-retardant, cross-linked EPDM rubber, according to an embodiment;

FIG. 2 is a chemical reaction diagram showing the preparation of aflame-retardant, cross-linked EPDM rubber, according to anotherembodiment; and

FIG. 3 is a flow diagram showing a particular embodiment of a process offorming a flame-retardant, cross-linked EPDM rubber.

V. DETAILED DESCRIPTION

The present disclosure relates to flame-retardant, cross-linked EPDMrubber materials and methods of preparing flame-retardant, cross-linkedEPDM rubber materials. In the present disclosure, ring-openingmetathesis polymerization may be used to polymerize a mixture of anethylene monomer (e.g., chlorinated ethylene, in some cases), apropylene monomer, and a diene monomer to form an EPDM terpolymer. TheEPDM terpolymer may be chemically reacted with a norbornene-basedphosphinate cross-linking material to form a flame-retardant,cross-linked EPDM rubber. Utilization of a norbornene-based phosphinatematerial as a cross-linking agent may allow for incorporation of a flameretardant agent (phosphorus) directly into a backbone of an EPDM rubbermaterial. Further, in cases where a chlorinated ethylene monomer is usedto form the EPDM terpolymer, the incorporation of chlorine into the EPDMterpolymer chains may provide additional flame retardancy benefits.

Referring to FIG. 1, a chemical reaction diagram 100 illustrates thepreparation of a flame-retardant, cross-linked EPDM rubber, according toone embodiment. FIG. 1 illustrates three chemical reactions. Thechemical reaction depicted at the bottom of FIG. 1 illustrates thepolymerization of a mixture that includes a chlorinated ethylenemonomer, a propylene monomer, and a diene monomer to form a chlorinatedEPDM terpolymer using ROMP. The chemical reaction depicted at the top ofFIG. 1 illustrates the preparation of a norbornene-based phosphinatecross-linking material. The chemical reaction depicted in the middle ofFIG. 1 illustrates that the norbornene-based phosphinate material may beused as a cross-linking agent to form a flame-retardant, cross-linkedchlorinated EPDM rubber.

Referring to the chemical reaction depicted at the bottom of FIG. 1, achlorinated ethylene monomer, a propylene monomer, and a diene monomermay be combined to form a mixture. FIG. 1 illustrates that, in somecases, 5-propylidene-2-norbornene may be used as the diene monomer(where R=CH₃), while in other cases the diene monomer may include5-ethylidene-2-norbornene (where R=H), also referred to herein as ENB.Alternatively, the diene monomer may include a combination of5-propylidene-2-norbornene and 5-ethylidene-2-norbornene, among otheralternative and/or additional diene monomers.

In a particular embodiment, a weight percentage of the ethylene monomer(chlorinated ethylene, in this case) may be in a range of 30 to 80weight percent of the mixture. In a particular embodiment, a weightpercentage of the diene monomer may be in a range of 2 to 10 weightpercent of the mixture. A weight percentage of the propylene monomer maybe in a range of 10 weight percent to 68 weight percent, depending onthe relative weight percentages of the ethylene/diene monomers in themixture. It will be appreciated that the weight percentages of themonomers may be selected in order to form an EPDM terpolymer with afirst portion (illustrated by the integer m) corresponding to thechlorinated ethylene monomer, a second portion (illustrated by theinteger n) corresponding to the propylene monomer, and a third portion(illustrated by the integer o) corresponding to the diene monomer.

FIG. 1 illustrates that the mixture may be polymerized using ROMPchemistry (e.g., using one or more catalyst materials and heat). In aparticular embodiment, a mixture of Cp*TiMe₃ and B(C₆F₅)₃ may beutilized as a catalyst material for ring-opening metathesispolymerization in order to form the chlorinated EPDM terpolymerillustrated in the example of FIG. 1. While not shown in FIG. 1, in somecases, at least a portion of the catalyst material(s) may remain afterthe ring-opening metathesis polymerization. In some cases, trace amountsof catalyst (e.g., at least a portion of the mixture of the Cp*TiMe₃ andB(C₆F₅)₃ catalyst materials) in a flame-retardant, cross-linkedchlorinated EPDM rubber may be indicative of ROMP chemistry having beenused to form a chlorinated EPDM terpolymer that is chemically reactedwith a norbornene-based phosphinate cross-linking material (as shown inthe chemical reaction depicted in the middle of FIG. 1).

Prophetic Example: Preparation of a Chlorinated EPDM Terpolymer

To a cooled (8° C.) glass reactor containing a solution of Cp*TiMe₃ (14mg, 0.06 mmol) in 5 mL of toluene, a cooled (8° C.) solution of B(C₆F₅)₃(31 mg, 0.06 mmol) in 5 mL of toluene may be added. The mixture may bebubbled for about 10 minutes through a mixture of vinyl chloride andpropylene (e.g., in about a 1:1 ratio). To the EPDM polymerizationreaction, diene monomer such as ENB (e.g., about 2-10 wt %) may be addedprior to the addition of B(C₆F₅)₃. Bubbling of the vinylchloride/propylene mixture through the stirred, cooled solution may becontinued for about 5-10 minutes. After reaction time, the viscousmixture may be treated with methanol (5 mL). The reaction temperatureduring polymerization may increase to about 18° C. and may remainconstant until termination of the reaction. The resultant chlorinatedEPDM terpolymer may then be purified. In some cases, trace amounts ofcatalyst material (e.g., Cp*TiMe₃ and/or B(C₆F₅)₃) may remain afterpurification.

Referring to the chemical reaction diagram depicted at the top of FIG.1, an example process of preparing a norbornene-based phosphinatecross-linking material is illustrated. FIG. 1 depicts an example inwhich a norbornene-based alcohol is chemically reacted with aphosphinate material to form the norbornene-based phosphinatecross-linking material. In the particular embodiment illustrated in FIG.1, the norbornene-based alcohol includes 5-norbornene-2-methanol, andthe phosphinate material includes3-(hydroxyl(phenyl)phosphoryl)propanoic acid. In other cases,alternative and/or additional norbornene-based alcohol(s) and/orphosphinate material(s) may be selected. As depicted in the chemicalreaction diagram illustrated in the middle of FIG. 1, relief of ringstrain in the norbornene-based phosphinate cross-linking material mayallow for phosphorus (P) to be directly attached to polymer chains of achlorinated EPDM terpolymer in order to impart flame retardancycharacteristics to a resulting cross-linked chlorinated EPDM rubber.

Prophetic Example: Preparation of Norbornene-Based PhosphinateCross-Linking Material

To a 250 mL round bottom flask fitted with a condenser,5-Norbornene-2-methanol (100 mL) may be added followed by3-(hydroxyl(phenyl)phosphoryl)propanoic acid (149 mmol) to form amixture. The mixture may then be stirred under ambient temperature.Sulfuric acid (3.66 g; 37.3 mmol) may be added, followed by heating thereaction to about 65° C. and holding for about 3 hours. After reaction,the solution may be cooled below room temperature for about 6 hours toallow precipitation. The product may then be purified.

Referring to the chemical reaction illustrated in the middle of FIG. 1,the chlorinated EPDM terpolymer (after using a Ziegler catalyst to forman intermediate material, illustrated via the replacement of the letterR with the letter M in FIG. 1) may be chemically reacted with thenorbornene-based phosphinate cross-linking material to form aflame-retardant, cross-linked chlorinated EPDM rubber. In a particularembodiment, an amount of norbornene-based phosphinate cross-linkingmaterial that is chemically reacted with the chlorinated EPDM terpolymermay be selected based on a desired degree of cross-linking, a desiredweight percentage of phosphorus (P) to impart particular flameretardancy characteristics, or a combination thereof. In FIG. 1, theinteger p is used to represent cross-linking locations. A degree ofcross-linking may be adjusted by varying a stoichiometric ratio of thechlorinated EPDM terpolymer and the norbornene-based phosphinatecross-linking material.

In a particular embodiment, an amount of norbornene-based phosphinatecross-linking material that is chemically reacted with the chlorinatedEPDM terpolymer may be sufficient for the flame-retardant, cross-linkedchlorinated EPDM rubber to satisfy one or more plastics flammabilitystandards. In some cases, additional flame retardant “packages” may beadded in order to satisfy plastics flammability standard(s). Toillustrate, a plastics flammability standard may be associated withheat-shrink tubing. As an example, the plastics flammability standard(e.g., associated with heat-shrink tubing) may include a burning stoprate of not greater than 60 seconds on a vertical specimen of an articleof manufacture that includes the flame-retardant, cross-linkedchlorinated EPDM rubber (e.g., EPDM rubber tubing for a water coolingapplication). In some cases, the plastics flammability standard mayallow drips of non-inflamed particles but may not allow drips of flamingparticles.

Prophetic Example: Cross-Linking of Chlorinated EPDM Terpolymer

To an internal mixer, chlorinated EPDM (94.3 wt %), elemental sulfur(0.7 wt %), an accelerator (such as MBT; 1 wt %), zinc oxide (3 wt %),and steric acid (1 wt %) may be added. Accelerators and activators andvulcanizing routes (e.g., sulfur, peroxide, etc.) may be selected by oneof ordinary skill in the art. To the reaction,(3-((bicycle[2.2.1]hept-5-en-2-ylmethyl)peroxy)propyl)(phenyl)phosphinicacid (e.g., 1 equiv.) may be added. The mixture may then be heated in aninternal mixture to about 130-140° C. The rubber may be cured at about160-180° C.

Thus, FIG. 1 illustrates an example of a process of preparing aflame-retardant, cross-linked chlorinated EPDM rubber (e.g., for use asEPDM rubber tubing for a water cooling application, among otheralternative uses). In the example of FIG. 1, the ethylene monomer (asshown in the chemical reaction illustrated at the bottom of FIG. 1) ischlorinated ethylene, resulting in the formation of a chlorinated EPDMterpolymer using ROMP chemistry. The chlorinated EPDM terpolymer maythen be chemically reacted with a norbornene-based phosphinatecross-linking material to form a flame-retardant, cross-linkedchlorinated EPDM rubber. FIG. 1 illustrates that utilization of anorbornene-based phosphinate material as a cross-linking agent may allowfor incorporation of a flame retardant agent (phosphorus) directly intoa backbone of an EPDM rubber material. Further, the incorporation of ahalogen, such as chlorine, into the EPDM terpolymer chains may provideadditional flame retardancy benefits.

Referring to FIG. 2, a chemical reaction diagram 200 illustrates thepreparation of a flame-retardant, cross-linked EPDM rubber, according toanother embodiment. FIG. 2 illustrates two chemical reactions. Thechemical reaction depicted at the bottom of FIG. 2 illustrates thepolymerization of a mixture that includes an ethylene monomer, apropylene monomer, and a diene monomer to form an EPDM terpolymer usingROMP chemistry. The chemical reaction depicted at the top of FIG. 2illustrates that a norbornene-based phosphinate material may be used asa cross-linking agent to form a flame-retardant, cross-linked EPDMrubber. In a particular embodiment, the norbornene-based phosphinatematerial depicted in the example of FIG. 2 may be formed according tothe process described herein with respect to FIG. 1.

Referring to the chemical reaction depicted at the bottom of FIG. 2, anethylene monomer (ethylene, in contrast to the chlorinated ethylene ofFIG. 1), a propylene monomer, and a diene monomer may be combined toform a mixture. FIG. 2 illustrates that, in some cases,5-propylidene-2-norbornene may be used as the diene monomer (whereR=CH₃). In other cases, the diene monomer may include5-ethylidene-2-norbornene (where R=H), also referred to herein as ENB.Alternatively, the diene monomer may include a combination of5-propylidene-2-norbornene and 5-ethylidene-2-norbornene, among otheralternative and/or additional diene monomers.

It will be appreciated that the weight percentages of the monomers maybe selected in order to form an EPDM terpolymer with a first portion(illustrated by the integer w) corresponding to the ethylene monomer, asecond portion (illustrated by the integer x) corresponding to thepropylene monomer, and a third portion (illustrated by the integer y)corresponding to the diene monomer. As the embodiment illustrated inFIG. 2 does not include a halogen (e.g., Cl) in the polymer backbone, arelative weight percentage of the diene monomer may be increasedcompared to a weight percentage of diene monomer in the example ofFIG. 1. In some cases, the weight percentage of diene monomer may beadjusted such that, after cross-linking, an amount of phosphorus in theresulting cross-linked EPDM rubber is sufficient to satisfy one or moreplastics flammability standards, such as a standard associated withheat-shrink tubing.

FIG. 2 illustrates that the mixture may be polymerized using ROMPchemistry (e.g., using one or more catalyst materials and heat). In aparticular embodiment, a mixture of Cp*TiMe₃ and B(C₆F₅)₃ may beutilized as a catalyst material for ring-opening polymerization to formthe EPDM terpolymer illustrated in the example of FIG. 2. While notshown in FIG. 2, in some cases, at least a portion of the ROMP catalystmaterial(s) may remain after polymerization. In some cases, detection oftrace amounts of catalyst (e.g., at least a portion of the mixture ofthe Cp*TiMe₃ and B(C₆F₅)₃ catalyst materials) in a flame-retardant,cross-linked EPDM rubber may be indicative of ROMP chemistry having beenused to form a EPDM terpolymer that is chemically reacted with anorbornene-based phosphinate cross-linking material (as shown in thechemical reaction depicted at the top of FIG. 2).

Prophetic Example: Preparation of EPDM Terpolymer

To a cooled (8° C.) glass reactor containing a solution of Cp*TiMe₃ (14mg, 0.06 mmol) in 5 mL of toluene, a cooled (8° C.) solution of B(C₆F₅)₃(31 mg, 0.06 mmol) in 5 mL of toluene may be added. The mixture may bebubbled for about 10 minutes through a mixture of ethylene and propylene(e.g., in about a 1:1 ratio). To the EPDM polymerization reaction, dienemonomer such as ENB may be added prior to the addition of B(C₆F₅)₃.Bubbling of the ethylene/propylene mixture through the stirred, cooledsolution may be continued for about 5-10 minutes. After reaction time,the viscous mixture may be treated with methanol (5 mL). The reactiontemperature during polymerization may increase to about 18° C. and mayremain constant until termination of the reaction. The resultant EPDMterpolymer may then be purified. In some cases, trace amounts ofcatalyst material (e.g., Cp*TiMe₃ and/or B(C₆F₅)₃ may remain afterpurification.

Referring to the chemical reaction illustrated at the top of FIG. 2, theEPDM terpolymer (after forming an intermediate material using a Zieglercatalyst, identified by the replacement of the letter R with the letterM in FIG. 2) may be chemically reacted with a norbornene-basedphosphinate cross-linking material to form a flame-retardant,cross-linked EPDM rubber. FIG. 2 illustrates that the norbornene-basedphosphinate cross-linking material may correspond to thenorbornene-based phosphinate cross-linking material formed according tothe process described with respect to FIG. 1. In a particularembodiment, an amount of norbornene-based phosphinate cross-linkingmaterial that is chemically reacted with the EPDM terpolymer may beselected based on a desired degree of cross-linking, a desired weightpercentage of phosphorus (P) to impart particular flame retardancycharacteristics, or a combination thereof. In FIG. 2, the integer z isused to represent cross-linking locations. A degree of cross-linking maybe adjusted by varying a stoichiometric ratio of the EPDM terpolymer andthe norbornene-based phosphinate cross-linking material.

In a particular embodiment, an amount of norbornene-based phosphinatecross-linking material that is chemically reacted with the EPDMterpolymer may be sufficient for the flame-retardant, cross-linked EPDMrubber to satisfy one or more plastics flammability standards. In somecases, additional flame retardant “packages” may be added in order tosatisfy plastics flammability standard(s), such as a plasticsflammability standard associated with heat-shrink tubing. As an example,a plastics flammability standard may include a burning stop rate of notgreater than 60 seconds on a vertical specimen of an article ofmanufacture that includes the flame-retardant, cross-linked EPDM rubber(e.g., EPDM rubber tubing for a water cooling application). In somecases, the plastics flammability standard may allow drips ofnon-inflamed particles but may not allow drips of flaming particles.

Prophetic Example: Cross-Linking of EPDM Terpolymer

To an internal mixer, EPDM (94.3 wt %), elemental sulfur (0.7 wt %), anaccelerator (such as MBT; 1 wt %), zinc oxide (3 wt %), and steric acid(1 wt %) may be added. Accelerators and activators and vulcanizingroutes (e.g., sulfur, peroxide, etc.) may be selected by one of ordinaryskill in the art. To the reaction,(3-((bicycle[2.2.1]hept-5-en-2-ylmethyl)peroxy)propyl)(phenyl)phosphinicacid (1 equiv.) may be added. The mixture may then be heated in aninternal mixture to about 130-140° C. The rubber may be cured at about160-180° C.

Thus, FIG. 2 illustrates an example of a process of preparing aflame-retardant, cross-linked EPDM rubber (e.g., for use as EPDM rubbertubing for a water cooling application, among other alternative uses).In contrast to the example of FIG. 1, FIG. 2 illustrates an example inwhich a non-chlorinated ethylene monomer is used, resulting in theformation of an EPDM terpolymer using ROMP chemistry. The EPDMterpolymer may then be chemically reacted with a norbornene-basedphosphinate cross-linking material to form a flame-retardant,cross-linked EPDM rubber. FIG. 2 illustrates that utilization of anorbornene-based phosphinate material as a cross-linking agent may allowfor incorporation of a flame retardant agent (phosphorus) directly intoa backbone of an EPDM rubber material.

FIG. 3 is a flow diagram of a particular embodiment of a process 300 offorming a flame-retardant, cross-linked EPDM rubber. FIG. 3 illustratesthat ROMP chemistry may be used to form an EPDM terpolymer (e.g.,chlorinated/non-chlorinated EPDM), and the EPDM terpolymer may bechemically reacted with a norbornene-based phosphinate cross-linkingmaterial to form a flame-retardant, cross-linked EPDM rubber. FIG. 3illustrates that the flame-retardant, cross-linked EPDM rubber may beincorporated into an article of manufacture (e.g., an EPDM rubber hosefor use in water cooling applications, among other alternatives).

The process 300 includes forming an EPDM terpolymer by ring-openingmetathesis polymerization, at 302. As an example, referring to FIG. 1, achlorinated ethylene monomer, a propylene monomer, and a diene monomermay be combined to form a mixture, and the mixture may be polymerized toform the chlorinated EPDM terpolymer (e.g., using ROMP chemistry). Asanother example, referring to FIG. 2, an ethylene monomer, a propylenemonomer, and a diene monomer may be combined to form a mixture, and themixture may be polymerized to form the EPDM terpolymer (e.g., using ROMPchemistry).

The process 300 includes chemically reacting the EPDM terpolymer with anorbornene-based phosphinate cross-linking material to form aflame-retardant, cross-linked EPDM rubber, at 304. As an example,referring to FIG. 1, the chlorinated EPDM terpolymer may be chemicallyreacted with the norbornene-based phosphinate material to form theflame-retardant, cross-linked chlorinated EPDM rubber. As anotherexample, referring to FIG. 2, the EPDM terpolymer may be chemicallyreacted with the norbornene-based phosphinate material to form theflame-retardant, cross-linked EPDM polymer.

In the particular embodiment illustrated in FIG. 3, the process 300includes incorporating the flame-retardant, cross-linked EPDM rubberinto an article of manufacture, at 306. As an illustrative, non-limitingexample, the flame-retardant, cross-linked EPDM rubber material(s) ofFIG. 1 and/or FIG. 2 may be incorporated into an EPDM rubber hose foruse in a water cooling application (among other alternatives).

Thus, FIG. 3 illustrates an example of a process of forming aflame-retardant, cross-linked EPDM rubber via a chemical reaction of achlorinated/non-chlorinated EPDM terpolymer (formed via ROMP chemistry)with a norbornene-based phosphinate material. The norbornene-basedphosphinate material may allow for incorporation of phosphorus directlyinto an EPDM polymer backbone for flame retardancy as well ascross-linking of EPDM polymer chains.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thescope of the disclosure. Thus, the present disclosure is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope possible consistent with the principles and features asdefined by the following claims.

The invention claimed is:
 1. A process comprising: polymerizing amixture that includes an ethylene monomer, a propylene monomer, and adiene monomer to form an ethylene-propylene-diene (EPDM) terpolymer; andchemically reacting the EPDM terpolymer with a norbornene-basedphosphinate material to form a flame-retardant EPDM rubber.
 2. Theprocess of claim 1, wherein the ethylene monomer includes chlorinatedethylene.
 3. The process of claim 1, wherein the diene monomer includes5-ethylidene-2-norbornene, 5-propylidene-2-norbornene, or a combinationthereof.
 4. The process of claim 1, wherein forming the EPDM terpolymerincludes using a mixture of Cp*TiMe₃ and B(C₆F₅)₃ as a catalystmaterial.
 5. The process of claim 4, wherein at least a portion of thecatalyst material remains after formation of the flame-retardant EPDMrubber.
 6. The process of claim 1, further comprising chemicallyreacting a norbornene-based alcohol and a phosphinate material to formthe norbornene-based phosphinate material.
 7. The process of claim 6,wherein the norbornene-based alcohol includes 5-norbornene-2-methanol.8. The process of claim 6, wherein the norbornene-based phosphinatematerial includes 3-(hydroxyl(phenyl)phosphoryl)propanoic acid.
 9. Aprocess comprising: polymerizing a mixture that includes a chlorinatedethylene monomer, a propylene monomer, and a diene monomer to form achlorinated ethylene-propylene-diene (EPDM) terpolymer; chemicallyreacting a norbornene-based alcohol and a phosphinate material to form anorbornene-based phosphinate material; and chemically reacting thechlorinated EPDM terpolymer with the norbornene-based phosphinatematerial to form a flame-retardant chlorinated EPDM rubber.
 10. Theprocess of claim 9, wherein a weight percentage of the chlorinatedethylene monomer is in a range of 30 to 80 weight percent of themixture.
 11. The process of claim 9, wherein a weight percentage of thediene monomer is in a range of 2 to 10 weight percent of the mixture.12. The process of claim 9, wherein the norbornene-based alcoholincludes 5-norbornene-2-methanol.
 13. The process of claim 9, whereinthe norbornene-based phosphinate material includes3-(hydroxyl(phenyl)phosphoryl)propanoic acid.
 14. The process of claim13, wherein the diene monomer includes 5-ethylidene-2-norbornene,5-propylidene-2-norbornene, or a combination thereof.
 15. The process ofclaim 9, wherein forming the EPDM terpolymer includes using a mixture ofCp*TiMe₃ and B(C₆F₅)₃ as a catalyst material.
 16. The process of claim13, wherein the flame retardant EPDM rubber includes phosphorus in abackbone of the EPDM terpolymer.